Ukrainian pilot Nadezhda Savchenko has started another hunger strike while in Russian custody, according to her lawyer.

Lawyer Mark Feygin said in a Twitter post that Savchenko began a dry hunger strike on Wednesday, refusing both water and food.

A Russian court last month sentenced her to 22 years in prison after finding her guilty of complicity in the 2014 killing of two Russian journalists during fighting between Russia-backed rebels and the Ukrainian government in eastern Ukraine.

The verdict took effect on Tuesday after Savchenko decided not to appeal.

Savchenko has denied the charges and demanded to be returned to Ukraine. She has gone on several hunger strikes during her nearly two years in Russian detention.

The United States and European countries have joined Ukraine in urging her release.